title: Naringin-induced p21WAF1-mediated G(1)-phase cell cycle arrest via activation of the Ras/Raf/ERK signaling pathway in vascular smooth muscle cells.
abstract: The flavonoid naringin has been shown to play a role in preventing the development of cardiovascular disease. However, the exact molecular mechanisms underlying the roles of integrated cell cycle regulation and MAPK signaling pathways in the regulation of naringin-induced inhibition of cell proliferation in vascular smooth muscle cells (VSMCs) remain to be identified. Naringin treatment resulted in significant growth inhibition and G(1)-phase cell cycle arrest mediated by induction of p53-independent p21WAF1 expression; expression of cyclins and CDKs in VSMCs was also down-regulated. In addition, among the pathways examined, blockade of ERK function inhibited naringin-dependent p21WAF1 expression, reversed naringin-mediated inhibition of cell proliferation and decreased cell cycle proteins. Moreover, naringin treatment increased both Ras and Raf activations. Transfection of cells with dominant negative Ras (RasN17) and Raf (RafS621A) mutant genes suppressed naringin-induced ERK activity and p21WAF1 expression. Finally, naringin-induced reduction in cell proliferation and cell cycle protein was abolished in the presence of RasN17 and RafS621A mutant genes. The Ras/Raf/ERK pathway participates in p21WAF1 induction, leading to a decrease in cyclin D1/CDK4 and cyclin E/CDK2 complexes and in naringin-dependent inhibition of cell growth. These novel and unexpected findings provide a theoretical basis for preventive use of flavonoids to the atherosclerosis disease.
authors.affiliation: Department of Food and Biotechnology, Chungju National University, Chungju, Chungbuk 380-702, Republic of Korea.
authors.forename: Eo-Jin
authors.initials: EJ
authors.lastname: Lee
authors.forename: Gi-Seong
authors.initials: GS
authors.lastname: Moon
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Choi
authors.forename: Wun-Jae
authors.initials: WJ
authors.lastname: Kim
authors.forename: Sung-Kwon
authors.initials: SK
authors.lastname: Moon
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000502:physiology*; D044950:Flavanones / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects*; D011905:Genes, ras / Q000187:drug effects / Q000502:physiology*; D047468:Immunoprecipitation; D009154:Mutation / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D013936:Thymidine / Q000378:metabolism; D014162:Transfection; D048490:raf Kinases / Q000187:drug effects / Q000502:physiology*
chemical_list: C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D044950:Flavanones; D005419:Flavonoids; D048490:raf Kinases; D018844:Cyclin-Dependent Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; C005274:naringin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D013936:Thymidine